Remark 3.15 The author is aware of the fact that Theorem REF 
can be subsumed in a more general scheme of analysis, where the Fréchet
and the Mordukhovich subdifferentials are replaced with any subdifferential
\(\partial _\Box \) , axiomatically defined as in [1]},
and \((\mathbb {X},\Vert \cdot \Vert )\)  is supposed to be \(\partial _\Box \) -trustworthy, as meant
in [1]}).
It is clear that, following such an approach, the subdifferential condition
\((\ref {cap:Msubdfarcond})\)  should be expected to take a more involved form,
because of the need of employing fuzzy sum rules for the \(\partial _\Box \) 
subdifferential.

